TPX2 (Targeting Protein for Xklp2) is an evolutionary conserved microtubule-associated protein important for microtubule nucleation and mitotic spindle assembly. The protein was described as an activator of the mitotic kinase Aurora A in humans and the Arabidopsis AURORA1 (AUR1) kinase. In contrast to animal genomes that encode only one TPX2 gene, higher plant genomes encode a family with several TPX2-LIKE gene members (TPXL). TPXL genes of Arabidopsis can be divided into two groups. Group A proteins (TPXL2, 3, 4, and 8) contain Aurora binding and TPX2_importin domains, while group B proteins (TPXL1, 5, 6, and 7) harbor an Xklp2 domain. Canonical TPX2 contains all the above-mentioned domains. We confirmed using in vitro kinase assays that the group A proteins contain a functional Aurora kinase binding domain. Transient expression of Arabidopsis TPX2-like proteins in Nicotiana benthamiana revealed preferential localization to microtubules and nuclei. Co-expression of AUR1 together with TPX2-like proteins changed the localization of AUR1, indicating that these proteins serve as targeting factors for Aurora kinases. Taken together, we visualize the various localizations of the TPX2-LIKE family in Arabidopsis as a proxy to their functional divergence and provide evidence of their role in the targeted regulation of AUR1 kinase activity.

• Keywords
• Arabidopsis thaliana, aurora kinase 1, in vivo co-localization, kinase assay, phylogeny, targeting protein for Xklp2,
• MeSH
• Arabidopsis cytology   genetics   metabolism   MeSH
• Aurora Kinases metabolism   MeSH
• Microtubules metabolism   MeSH
• Protein Domains MeSH
• Microtubule-Associated Proteins analysis   genetics   metabolism   MeSH
• Arabidopsis Proteins analysis   genetics   metabolism   MeSH
• Genes, Plant MeSH
• Amino Acid Sequence MeSH
• Protein Binding MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Aurora Kinases MeSH
• Microtubule-Associated Proteins MeSH
• Arabidopsis Proteins MeSH
• TPX2 protein, Arabidopsis MeSH Browser